From my knowledge and experience, a lesser quantity of anti-freeze ratio enhances cooling capabilities. I run approx. 30% coolant to 70% water with "Water Wetter" added. It provides lubrication for the pump, protection from corrosion, and the system pressure is what controls the boiling point. From what I've found, pure water with 2 or 3 bottles of water wetter is the optimum for high temp. situations, disregarding freezing levels. (Something you probably won't encounter in your location.) I know of several OR racers that do pure water w/water wetter without any problems.

After reading all the posts in response to your problem, I'm stumped also. The only thing I can guess is possibly a blown head gasket or slipping impeller. A compression test will reveal one while the other is only identified/cured by replacement of the water pump. I had to replace a water pump 2 months after installation because the impeller walked off the end of the shaft and gouged the block a bit. It's not unheard of that a water pump fails shortly after installation. I wasn't happy!

It may be close enough to normal that you just need to keep an extra vigilent eye on the temp gauge, maybe even install a backup mechanical gauge just for insurance. It sounds like it's within specs, albeit on the high side of them.

I'm so paranoid that if mine gets above the upper white line, I find a place to stop and enjoy life for a bit. Mine usually doesn't budge much off the bottom white line (with my modifications), and knowing that it's safe to the upper white line...........I still don't push it. Getting accurate and setting your operational limits would be my starting point and I don't think the factory temp. gauge is a good reference. Mine tends to vary considerably, warmer on cool days and cooler on 100+ days. My cooling system is basically brand new with enhancements. I do run a 75C thermostat and fan switch with 30% anti-freeze and watter wetter. I also have replaced the viscous fan with an 18" 2500cfm electric fan mounted in the factory shroud in addition to the 16" factory aux. fan in front of the condenser. At anything other than bumper to bumper, it never gets more than 1/8th inch above the bottom white line.

I have worked on a few S4's that seemed to be close to overheating, but were well within specs. A friends 60k mile 89' with AutoAuthority chips resides around the upper white line, slightly above or below. After checking temps, he has a much better sense of comfort knowing that the gauge is going to be on the high side during normal running. I even put a 75C thermostat and switch in his car but it still sits at or above the upper white line in traffic w/A/C on. His radiator inlet temp is 210F and his outlet temp is 170F. I'm sure that the radiator hoses do radiate heat, but probably not a significant amount compared to the radiator. After trying every trick I know of, his car does not run much cooler by the gauge than before I started. But.........he has never overheated at 100+F in SLC with the A/C on.

I'd say that either it's something worth keeping a close eye on and living with, or getting crazy (as all of us are guilty of!) and replacing the water pump and/or head gaskets. I'm sure you are tired of answering questions that have been replied to repeatedly and can only hope I have helped a little bit. BTW,I also have disconnected the flaps at the connector just in front of the radiator on almost every S4 I have worked on just to insure that they stayed open. Getting warmed up isn't a problem here but staying cool is.

Keep us informed as to what you find...................

Dave

 

You know Ernest, with a little work the tank is hardly noticeable

 

Maybe I mistyped--

The localized boiling definitely contributes to heating problems. So, higher blow-off pressure means higher temp capability. If the cap is just leaking off steam (easy to test for with a catch bottle at the end of the drain tube...) you do risk that problem. But new caps are cheap and so easy to install that it's hardly worth 'testing' for.

How I Teach Troubleshooting 101:

-- Look at the things that changed just before the problem showed up. If you did a T-belt and WP job three months ago, and the heating showed up just after that, consider what might have happened as part of your work. Cam timing off a tooth? WP not pumping so well? Coolant leak through a bolt hole someplace?

-- Look at the things that are aesiest to eliminate. After all, troubleshooting is a logical procedure of eliminating the the possible causes until you find the one that saves you. The order of selection is based on likelyhood based on conditions, cost, ease of the fix, each with it's own K-factor assigned. Caps are cheap and quick, low probability of it being the only problem, but for less than $10 easy to eliminate for sure. Blown head gasket is low on the list becuase of low probability, high cost, high difficulty. Other stuff falls in between there someplace.

-- Take care of the basic maintenance stuff first before you go looking for exotic problems with exotic solutions. Cam timing is cheap to check. Plugs are easy to replace. Vacuum leaks easy to isolate. How many times have you heard about somebody fighting an erratic miss due to a loose plug wire boot or a worn/cracked cap? Baseline all the obvious maintenance stuff and lots of piddly 'problems' go away. Amazing!


Basic mechanical inspection often reveals a lot about the car's health. Compression gauge and vacuum gauge are great tools, timing light falls in there too. Car running a little warm? How's the compression --compared with the last time you checked it-- ? Stuff like this seems obvious only after it saves the day.


These are general concept things, not directed at what you are doing.

----------------


I'm very convinced that the S4 is not a car that likes to actually run cool. Too many things conspire to keep the temperature up in the motor, so many that one must wonder if the factory had a reason to keep the motor warm. I have the 85C thermostat installed, but still have the fans and the flap controllers original. Without the A/C on, all three limiters work together. With the A/C on. flaps go to full open and fans go to full speed no matter what the engine temp is, sometimes lets the engine cool down to the point where the thermostat starts to limit radiator flow. If I was serious about getting the beast to run down at the middle of the gauge, I'd be swapping in resistors in the fan/flap loop to the Temp Sensor II circuit to get the flaps and the fans going a little earlier.

If the gauge had a habit of creeping up on me even with the fans and flaps working, I'd look for a radiator, airflow, or water flow problem. (I posted a long diatribe on this stuff a couple years ago.) If the temp went up to some point that I thought was too high and pretty much parked there, I'd be looking at some of the controlling/measuring items to find what was limiting the cooling. As handy as the infrared heat gun is, there's no way to effectively look at component temps under load, so maybe a calibrated sensor and a separate meter might be the way to find out for sure what's going through the system. I see that it would be a snap to hook up an ohm meter to a sensor, drop it in the boiling water bath with a real thermometer, and get the calibration constants. Put the same values into the gauge and see what temps are actually indicated b the marks on the gauge face. Then I'd feel comfortable or uncomfortable about what the gauge reads. ;-)


Back to work!

 

Enjoyed the read Bob!


"If I was serious about getting the beast to run down at the middle of the gauge, I'd be swapping in resistors in the fan/flap loop to the Temp Sensor II circuit to get the flaps and the fans going a little earlier."


Bob, I find this to be an interesting avenue, care to share any in depth ideas on this?

 

Hello all, I've been following these little threads with some intrest. I have a suggestion to offer the forum. If a historical temp measurement is needed, there is a way to track temp readings in a variety of locations on the 928's engine bay through wireless devices called I-buttons. I've had a set of four of these sensors for some time and they are extremely useful in determining temperature changes over a period of time. They are the size of ~ 3 nickles stacked on each other and are user programmed to monitor temp changes. The parameters are configurable to sample time and frequency of samples as well as mission duration. For example, you can set them up to record temps every second, minute, hour, etc.... This sampling continues for thousands of measurements. Once the car has been put though it's paces, the sensors are removed and docked into a station which is connected to a PC. All temp measurements are then downloaded to the PC and displayed in historical graphs. You can even set upper and lower control limits during the mission configuration which will indicate in the graph how many times temperature readings were out of their pre programmed settings. I think that if a set of these sensors were placed in strategic locations, it is possible to compare the results and accurately narrow down a likely root cause if there indeed is a temp problem.

 

Hey Ernest -

So where are you at regarding the OH issue?. Any headway yet?.

TIA

 

Oscar,
Thanks for the suggestion. I don't think that accurate measurement is my problem, I think it's the actual temperature.
Drew,
Actually, the one thing that seems to have helped the most is the repositioning of that flap in the bottom air intake. The later cars have two horizontal intakes in the front bumper cover split down the middle vertically. There seems to be a thin piece of material on the top of the chin spoiler that's supposed to be tucked under the bottom lip of the bottom intake. That material had moved up into the air flow and, I suspect, was pushed up even further at speed when the air pressure from below increased. Since repositioning it the car is running, at most, about a needle width over the last white line, which represents about 193F. Because of that change, and since I noticed a fair amount of debris, mostly sand, in the original radiator fins, I'm trying to figure a way to get some compressed air down behind the AC condenser and really blow it out well.

 

Thanks for status update. Maybe you can just blow it from behind the radiator?.

Good Luck

 

Oscar, tell me where I can get some more information on those little sensors and the system that drives it!

Is there a website you can point me to?

 

Sterling,
No flaps on a 91.

 

Hey Max,

Here's the website.

See you at Blanco!

https://store.ibutton.com/cgi-bin/nc...nbr=776&cg=810

 

Red UFO: Can we get bumper stickers of your signature line? I love it. Of course I would never put it on the shark. It would invite surveillance. I have one that says, "Politicians and diapers should be periodically changed -- often for the same reason."

 

Thanks Oscar that's a nice site with tons of information. Do you have any first hand or BTDT information on these little units?

 

Hi,

Ernest - on the 19/8 when you were concerned about my ability to read
( flippant I'm sure ) and in your preoccupation with Joe Lights Off and BMC, you did not answer my question about oil cooler temperature measurements and the brand, type and viscosity of the oil you use

For your interest I'm also fluent in Danish ( og "Skansk", Eric og Sweanders ), and reasonable in German and Italian too!

I only hope YOU can read this - its written in genuine BMC ENGLISH!!!

Penned in peace in the Australian Tropics

Regards

 

Hej Doug,
Det var hyggeligt at høre der er en 'there downunder' som taler Dansk
Kan du også sige 'Rødgrød med Fløde'?
from Erik in Denmark